Moisture-resistant aluminum nitride powder and methods of making and using

Abstract

Moisture-resistant aluminum nitride powder which is treated with an yttrium-containing compound. The method of treating the aluminum nitride compound includes (a) thoroughly mixing a slurry containing aluminum nitride powder, an yttrium-containing compound, and a solvent for the yttrium-containing compound in the absence of any surfactant and (b) removing the solvent from the slurry. The moisture-resistant aluminum nitride powder may be used in aqueous formulations for making ceramic articles.

What is claimed is: 
     
       1. A method of preparing an aqueous slip containing moisture-resistant aluminum nitride powder, comprising: (a) thoroughly mixing a slurry consisting essentially of aluminum nitride, powder, an yttrium-containing compound, and a solvent for the yttrium-containing compound in the absence of any surfactant,   (b) removing the solvent from the slurry to form dry moisture-resistant aluminum nitride powder uniformly coated with the yttrium-containing compound, and   (c) dispersing the dry moisture-resistant aluminum nitride powder and ceramic composite components in an aqueous medium wherein the aqueous medium is employed in an amount from about 20 to about 80 weight percent and the dry moisture-resistant aluminum nitride powder and the ceramic composite components are employed in an amount from about 20 to about 80 weight percent wherein the weight percents of the aqueous medium and the dry moisture-resistant aluminum nitride powder and the ceramic composite components total 100 percent.   
     
     
       2. The method of claim 1, wherein the moisture-resistant aluminum nitride powder is treated with the yttrium-containing compound in an amount from about 0.1 to about 10 weight percent as yttrium oxide. 
     
     
       3. The method of claim 1, wherein the moisture-resistant aluminum nitride powder is treated with the yttrium-containing compound in an amount from about 0.1 to about 0.4 weight percent as yttrium oxide. 
     
     
       4. The method of claim 1, wherein the yttrium-containing compound is selected from the group consisting of yttrium nitrate, yttrium sulfate, yttrium carbonate, yttrium alkoxide, and mixtures thereof. 
     
     
       5. The method of claim 1, wherein the solvent is selected from the group consisting of polar organic liquids and mixtures thereof. 
     
     
       6. A method of preparing an aqueous slip containing moisture-resistant aluminum nitride powder, comprising: (a) thoroughly mixing a slurry consisting essentially of aluminum nitride powder, an yttrium-containing compound selected from the group consisting of yttrium nitrate, yttrium sulfate, yttrium carbonate, yttrium alkoxide, and mixtures thereof, and a solvent for the yttrium-containing compound in the absence of any surfactant, the yttrium-containing compound employed in an amount from about 0.1 to about 10 weight percent of the aluminum nitride powder as yttrium oxide, the solvent selected from the group consisting of polar organic liquids and mixtures thereof,   (b) removing the solvent from the slurry to form dry moisture-resistant aluminum nitride powder uniformly coated with the yttrium-containing compound, and   (c) dispersing the dry moisture-resistant aluminum nitride powder and ceramic composite components in an aqueous medium wherein the aqueous medium is employed in an amount from about 20 to about 80 weight percent and the dry moisture-resistant aluminum nitride powder and the ceramic composite components are employed in an amount from about 20 to about 80 weight percent wherein the weight percents of the aqueous medium and the dry moisture-resistant aluminum nitride powder and the ceramic composite components total 100 percent.   
     
     
       7. A method of preparing a sintered aluminum nitride ceramic article, comprising: (a) thoroughly mixing a slurry consisting essentially of aluminum nitride powder, an yttrium-containing compound, and a solvent for the yttrium-containing compound in the absence of any surfactant,   (b) removing the solvent from the slurry to form dry moisture-resistant aluminum nitride powder uniformly coated with the yttrium-containing compound,   (c) dispersing the dry moisture-resistant aluminum nitride powder and ceramic composite components in an aqueous medium to form a slip wherein the aqueous medium is employed in an amount from about 20 to about 80 weight percent and the dry moisture-resistant aluminum nitride powder and the ceramic composite components are employed in an amount from about 20 to about 80 weight percent wherein the weight percents of the aqueous medium and the dry moisture-resistant aluminum nitride powder and the ceramic composite components total 100 percent,   (d) removing the aqueous medium from the slip to form composite powder,   (e) shaping the composite powder, and   (f) sintering the shaped composite powder to form the sintered aluminum nitride ceramic article.   
     
     
       8. The method of claim 7, wherein the moisture-resistant aluminum nitride powder is treated with the yttrium-containing compound in an amount from about 0.1 to about 10 weight percent as yttrium oxide. 
     
     
       9. The method of claim 7, wherein the moisture-resistant aluminum nitride powder is treated with the yttrium-containing compound in an amount from about 0.1 to about 0.4 weight percent as yttrium oxide. 
     
     
       10. The method of claim 7, wherein the yttrium-containing compound is selected from the group consisting of yttrium nitrate, yttrium sulfate, yttrium carbonate, yttrium alkoxide, and mixtures thereof. 
     
     
       11. The method of claim 7, wherein the solvent is selected from the group consisting of polar organic liquids and mixtures thereof.